title: Enhanced β-turn conformational stability of tripeptides containing ΔPhe in cis over trans configuration.
abstract: Conformations of three pairs of dehydropeptides with the opposite configuration of the ΔPhe residue, Boc-Gly-Δ(Z/E)Phe-Phe-p-NA (Z- p -NA and E- p -NA), Boc-Gly-Δ(Z/E)Phe-Phe-OMe (Z-OMe and E-OMe), and Boc-Gly-Δ(Z/E)Phe-Phe-OH (Z-OH and E-OH) were compared on the basis of CD and NMR studies in MeOH, TFE, and DMSO. The CD results were used as the additional input data for the NMR-based calculations of the detailed solution conformations of the peptides. It was found that Z- p -NA, E- p -NA, Z-OMe, and Z-OH adopt the β-turn conformations and E-OMe and E-OH are unordered. There are two overlapping type III β-turns in Z- p -NA, type II' β-turn in E- p -NA, and type II β-turn in Z-OMe and Z-OH. The results obtained indicate that in the case of methyl esters and peptides with a free carboxyl group, Δ(Z)Phe is a much stronger inducer of ordered conformations than Δ(E)Phe. It was also found that temperature coefficients of the amide protons are not reliable indicators of intramolecular hydrogen bonds donors in small peptides.
authors.affiliation: Department of NMR-based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany, antypater@gmail.com.
authors.forename: Mariusz
authors.initials: M
authors.lastname: Jaremko
authors.forename: Lukasz
authors.initials: L
authors.lastname: Jaremko
authors.forename: Adam
authors.initials: A
authors.lastname: Mazur
authors.forename: Maciej
authors.initials: M
authors.lastname: Makowski
authors.forename: Marek
authors.initials: M
authors.lastname: Lisowski
mesh_terms: D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry*; D011487:Protein Conformation; D055550:Protein Stability; D013237:Stereoisomerism
chemical_list: D009842:Oligopeptides; D010649:Phenylalanine